Qualification of design-optimized multi-zone hotplate for 45nm node mask making
Abstract
The demand for ever smaller features in integrated circuit manufg. continues to put more stringent requirements on photomask fabrication, particularly with respect to crit. dimension (CD) control. A high resoln. process for making attenuated-phase-shift masks (attPSM) for the 45nm node with a neg.-tone chem. amplified resist (nCAR), utilizing a new precision bake system, was evaluated. This process showed a significant performance improvement in crit. dimension uniformity (CDU), resp. to an established process based on an APB5500 system. A CD-uniformity improvement from 2.1nm CD 3s to 1.3nm CD 3s (40%) was achieved on a demanding layout. The new precision bake system utilizes an improved multi-zone hotplate design and control algorithm, which enables highly precise temp. controllability, facilitating a superior temp. ramp-up performance, as well as significantly improved temp. setpoint stability, as has been measured with a 25-point sensor mask for a 95 DegC bake process. The new precision bake system shall now be introduced to the market within the HamaTech MaskTrack series.
